Virus Monitoring and Removal in Natural and Built Systems

The importance of an adequate response has been highlighted as never before by the current COVID-19 pandemic. In their recent paper, McDonald et al. (2018) considered a pandemic influenza outbreak as a case study of significant disruption and modeled how interconnected infrastructures could respond to mitigate the effects of the outbreak. With high relevance for the 2020 pandemic, the use of antivirals and masks and quarantine policies are considered in the paper. In their contribution to the Leadership and Management in Engineering journal, Vallero and Letcher (2012) drew lessons on risk assessment and disaster management based on past crises viewed in the context of the failure type, including miscalculations, extraordinary natural circumstances, critical path, negligence, and inaccurate prediction of contingencies.

Timely detection and accurate quantitative assessment of microbial threats are of utmost importance for mounting effective countermeasures and protecting public health. Specifically, rapid detection of viral nucleic acid in water and wastewater enables early warning of possible microbial threats to communities. This challenge calls for the development of rapid sensing technologies and data-based modeling approaches to accurately track viruses in environmental media. In a recent example of such an approach, Chen et al. (2008) employed seminested reverse transcriptase polymerase chain reaction (PCR) to quantify enteroviruses in a brackish water source in Taiwan. In their case study, Elkayam et al. (2018) point out the value of microbial source tracking data as guidance to regulatory agencies on the performance of treatment systems. Papp et al. (2020) employed viral surrogates to evaluate performance of a membrane bioreactor and a full advanced treatment in potable water reuse. McCall and Xagoraraki (2019) reviewed applications of metagenomics in virus detection and discussed both best practices for quantifying the diversity of viruses and the limitations of virus detection by next-generation sequencing methods.

Monitoring pathogen transport and predicting the fate of pathogenic microorganisms in water are critical for public health. A wealth of applied engineering research has been performed to develop models and effectively predict the occurrence and concentrations of pathogens in the natural environment and engineering processes. Indeed, the monitoring of viral pathogens and indicators has been subject to extensive research, with a large number of studies focusing on tracking and measuring viruses in water and wastewater treatment systems. Three recent papers (Xagoraraki et al. 2014; Yin et al. 2018; O’Brien and Xagoraraki 2020) addressed virus fate in water utilities including membrane bioreactor plants in particular. Two of these papers were published as state-of-the-art reviews (Xagoraraki et al. 2014; O’Brien and Xagoraraki 2020) where the authors critically examined published literature to identify sources, reservoirs, and the fate of viruses in water systems. The papers explore the use of viruses as microbial source tracking tools and discuss a range of related issues, including virus survival, virus transport, and methods of detection (Xagoraraki et al. 2014). Virus transport and attenuation in natural systems has been another focus of active research. The work included source tracking as in the study by Gandhi et al. (2017), who emphasized the importance of identifying virus sources to control the spread of epidemics. Virus fate in groundwater system has been explored by Bhattacharjya et al. (2015) and Ojha et al. (2012), who studied transport in groundwater aquifers and the unsaturated zone, respectively.

Environmental engineers have the responsibility to implement engineering interventions for reducing risks associated with water- and airborne pathogens and safeguarding public health. This goal is achieved by the removal or inactivation of pathogens (O’Brien and Xagoraraki 2020; Baxter et al. 2007; Hendricks et al. 2005) through disinfection and disruption of pathogen transmission routes. Multibarrier approaches are developed through careful consideration of a number of factors. First, identifying the transmission routes is a critical aspect of designing the treatment approach (Baxter et al. 2007; Casabuena et al. 2019). For instance, given that the current research suggests COVID-19 infection primarily occurs via direct surface contact or inhalation of viral droplets and aerosols, disinfection should target fomites and air. Meanwhile, disinfection for water and wastewater is needed due to the concerns over the fecal transmission route of SARS-CoV-2. Furthermore, virus-laden wastewater may generate viral aerosols and thus poses a secondary threat to end users and wastewater treatment and reuse professionals. Second, disinfection treatment should be appropriately selected and optimized. Disinfection, at a household level or a larger scale, can partially or completely inactivate pathogens through exposure to (1) chemical agents such as free or combined chlorine, chlorine dioxide, ozone, heavy metals, and mixed chemicals generated from electrochemical oxidation (Fang et al. 2006); and (2) physical processes like ultraviolet (UV) (Oguma et al. 2016; Lim and Blatchley 2012) and gamma irradiation (Thompson and Blatchley 2000). Special attention should be paid to emerging disinfecting agents such as ferrate(VI). Of note, most studies on virus inactivation focused on nonenveloped human enteric viruses (e.g., noroviruses and enteroviruses) (Brewster et al. 2005), rather than enveloped viruses such as SARS-CoV-2, Ebola, MERS-CoV, SARS-CoV, and Zika. However, enveloped viruses are generally more readily inactivated than nonenveloped ones. Third, secondary disinfection is needed to provide disinfectant residual to inhibit pathogen regrowth in a water distribution system. Chlorine and other disinfectants with a slow decay rate, rather than more powerful agents (e.g., ozone) having a much shorter lifetime, are typically adopted for secondary disinfection.

At the same time, disinfection may have adverse impacts that need to be considered. Increased exposure to disinfectants typically entails the formation of more disinfection by-products (DBPs). Further, residual disinfectants, particularly those that are chlorine based, can find their way to natural ecosystems through runoff or sewers and then threaten ecological and human health by affecting the microbial community and by introducing DBPs. Higher usage and exposure to disinfectant at the time of sanitary crises such as the ongoing COVID-19 pandemic bring these issues to the fore. While high efficiency of disinfection is the primary consideration, adverse effects of DBPs on public health and the natural environment should also be considered.

There is an increasing realization that critical elements of built infrastructure are vulnerable, with potentially dire consequences. Cyberattacks, industrial accidents, extreme weather events, and failures due to aging are examples of possible causes of disruption. In relation to water infrastructure, vulnerabilities present challenges for maintaining the required water quality and in ensuring water is available for vital uses. This special collection includes several contributions that address these important challenges. Hassanzadeh et al. (2020) review disruption occurrences in the water distribution segment to devise protection against malicious cybersecurity threats. Protection measures are presented in the context of manufacturing control system architectures, attack-defense models, and security resolutions. Given the rise of new cyber threats (e.g., ransomware or cryptojacking), the review emphasizes a cooperative, adaptive, and comprehensive approach to water cyber defense. Similarly, Shin et al. (2020) characterize the resilience of water cyber-physical systems and explore probable resilience approaches. They recommend a progressive resilience measure that assimilates the withstanding, absorptive, adaptive, and restorative abilities of a structure introduced and functional to the water distribution network for nearly 15 disaster set situations. Finally, Han et al. (2014) describe the early warning system for organic and inorganic chemicals and sewage that provides real-time detection of these pollutants in drinking water supply systems. Both intentional acts (e.g., cyberattacks) and natural disasters (e.g., hurricanes, tsunamis, earthquakes, landslides, heat waves, droughts, cold spells) can have a severe impact. The primary consequences are damage to infrastructure and property and loss of life. Secondary effects include a decline in productivity, investment risk, liability, and human health impacts. Systematic research on modeling and cyber systems could help manage risks that such crises entail.

This special collection is envisioned as an ongoing effort, and we invite new contributions. The Call for Papers can be found at https://ascelibrary.org/page/callforpapers. Individual papers accepted for publication will appear in print, spread over different regular issues of the ASCE Journal of Environmental Engineering. Each will be marked as a part of the Virus Monitoring and Removal in Natural and Built Systems special collection and added to the ASCE Library (https://ascelibrary.org/joeedu/virus_monitoring_built_systems).